685969 has 2 divisors, whose sum is σ = 685970. Its totient is φ = 685968.

The previous prime is 685963. The next prime is 685973. The reversal of 685969 is 969586.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 620944 + 65025 = 788^2 + 255^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-685969 is a prime.

It is a super-2 number, since 2×685969² = 941106937922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (685963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342984 + 342985.

It is an arithmetic number, because the mean of its divisors is an integer number (342985).

2⁶⁸⁵⁹⁶⁹ is an apocalyptic number.

It is an amenable number.

685969 is a deficient number, since it is larger than the sum of its proper divisors (1).

685969 is an equidigital number, since it uses as much as digits as its factorization.

685969 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 43.

The square root of 685969 is about 828.2324552926. The cubic root of 685969 is about 88.1931449844.

The spelling of 685969 in words is "six hundred eighty-five thousand, nine hundred sixty-nine".